As technology development and demand for mobile devices have increased, demand for a secondary battery as an energy source has rapidly increased. Conventionally, a nickel-cadmium battery or a hydrogen ion battery has been used as the secondary battery. However, a lithium secondary battery is recently widely used because charging and discharging is free due to rare memory effect in comparison with a nickel-based secondary battery, a self-discharge rate is very low, and an energy density is high.
Such lithium secondary battery mainly uses a lithium oxide and a carbonaceous material as a positive electrode active material and a negative electrode active material, respectively. The lithium secondary battery includes an electrode assembly in which a positive electrode plate and a negative electrode plate, respectively coated with the positive electrode active material and the negative electrode active material, are arranged with a separator therebetween, and a packaging member, that is, a battery case, which seals and receives the electrode assembly together with an electrolyte solution.
The lithium secondary battery includes the positive electrode, the negative electrode, the separator therebetween, and an electrolyte. Depending on a type of the positive electrode active material and the negative electrode active material being used, the lithium secondary battery is divided into a lithium ion battery (LIB), a lithium polymer ion battery (LPIB), and etc. Typically, an electrode of the lithium secondary battery is formed by applying the positive electrode active material or the negative electrode active material to a current collector such as a sheet, a mesh, a film, and a foil of aluminum or copper and then drying the applied positive electrode active material or negative electrode active material.
Generally, a battery module of the secondary battery may be combined with a plate by using a welding method or the like in order to protect internal components from vibration or shock. In this case, it is a problem that injection-molded components of a plastic material arranged inside the battery module can be thermally deformed and damaged by heat generated during welding.